blob: ad17d1ff1b27c6051ee7ef18920c0eb701ef8525
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini weak password checker implementation for busybox |
4 | * |
5 | * Copyright (C) 2006 Tito Ragusa <farmatito@tiscali.it> |
6 | * |
7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
8 | */ |
9 | |
10 | /* A good password: |
11 | 1) should contain at least six characters (man passwd); |
12 | 2) empty passwords are not permitted; |
13 | 3) should contain a mix of four different types of characters |
14 | upper case letters, |
15 | lower case letters, |
16 | numbers, |
17 | special characters such as !@#$%^&*,;". |
18 | This password types should not be permitted: |
19 | a) pure numbers: birthdates, social security number, license plate, phone numbers; |
20 | b) words and all letters only passwords (uppercase, lowercase or mixed) |
21 | as palindromes, consecutive or repetitive letters |
22 | or adjacent letters on your keyboard; |
23 | c) username, real name, company name or (e-mail?) address |
24 | in any form (as-is, reversed, capitalized, doubled, etc.). |
25 | (we can check only against username, gecos and hostname) |
26 | d) common and obvious letter-number replacements |
27 | (e.g. replace the letter O with number 0) |
28 | such as "M1cr0$0ft" or "P@ssw0rd" (CAVEAT: we cannot check for them |
29 | without the use of a dictionary). |
30 | |
31 | For each missing type of characters an increase of password length is |
32 | requested. |
33 | |
34 | If user is root we warn only. |
35 | |
36 | CAVEAT: some older versions of crypt() truncates passwords to 8 chars, |
37 | so that aaaaaaaa1Q$ is equal to aaaaaaaa making it possible to fool |
38 | some of our checks. We don't test for this special case as newer versions |
39 | of crypt do not truncate passwords. |
40 | */ |
41 | |
42 | #include "libbb.h" |
43 | |
44 | static int string_checker_helper(const char *p1, const char *p2) __attribute__ ((__pure__)); |
45 | |
46 | static int string_checker_helper(const char *p1, const char *p2) |
47 | { |
48 | /* as sub-string */ |
49 | if (strcasestr(p2, p1) != NULL |
50 | /* invert in case haystack is shorter than needle */ |
51 | || strcasestr(p1, p2) != NULL |
52 | /* as-is or capitalized */ |
53 | /* || strcasecmp(p1, p2) == 0 - 1st strcasestr should catch this too */ |
54 | ) { |
55 | return 1; |
56 | } |
57 | return 0; |
58 | } |
59 | |
60 | static int string_checker(const char *p1, const char *p2) |
61 | { |
62 | int size, i; |
63 | /* check string */ |
64 | int ret = string_checker_helper(p1, p2); |
65 | /* make our own copy */ |
66 | char *p = xstrdup(p1); |
67 | |
68 | /* reverse string */ |
69 | i = size = strlen(p1); |
70 | while (--i >= 0) { |
71 | *p++ = p1[i]; |
72 | } |
73 | p -= size; /* restore pointer */ |
74 | |
75 | /* check reversed string */ |
76 | ret |= string_checker_helper(p, p2); |
77 | |
78 | /* clean up */ |
79 | nuke_str(p); |
80 | free(p); |
81 | |
82 | return ret; |
83 | } |
84 | |
85 | #define CATEGORIES 4 |
86 | |
87 | #define LOWERCASE 1 |
88 | #define UPPERCASE 2 |
89 | #define NUMBERS 4 |
90 | #define SPECIAL 8 |
91 | |
92 | #define LAST_CAT 8 |
93 | |
94 | static const char *obscure_msg(const char *old_p, const char *new_p, const struct passwd *pw) |
95 | { |
96 | unsigned length; |
97 | unsigned size; |
98 | unsigned mixed; |
99 | unsigned c; |
100 | unsigned i; |
101 | const char *p; |
102 | char *hostname; |
103 | |
104 | /* size */ |
105 | if (!new_p || (length = strlen(new_p)) < CONFIG_PASSWORD_MINLEN) |
106 | return "too short"; |
107 | |
108 | /* no username as-is, as sub-string, reversed, capitalized, doubled */ |
109 | if (string_checker(new_p, pw->pw_name)) { |
110 | return "similar to username"; |
111 | } |
112 | #ifndef __BIONIC__ |
113 | /* no gecos as-is, as sub-string, reversed, capitalized, doubled */ |
114 | if (pw->pw_gecos[0] && string_checker(new_p, pw->pw_gecos)) { |
115 | return "similar to gecos"; |
116 | } |
117 | #endif |
118 | /* hostname as-is, as sub-string, reversed, capitalized, doubled */ |
119 | hostname = safe_gethostname(); |
120 | i = string_checker(new_p, hostname); |
121 | free(hostname); |
122 | if (i) |
123 | return "similar to hostname"; |
124 | |
125 | /* Should / Must contain a mix of: */ |
126 | mixed = 0; |
127 | for (i = 0; i < length; i++) { |
128 | if (islower(new_p[i])) { /* a-z */ |
129 | mixed |= LOWERCASE; |
130 | } else if (isupper(new_p[i])) { /* A-Z */ |
131 | mixed |= UPPERCASE; |
132 | } else if (isdigit(new_p[i])) { /* 0-9 */ |
133 | mixed |= NUMBERS; |
134 | } else { /* special characters */ |
135 | mixed |= SPECIAL; |
136 | } |
137 | /* Count i'th char */ |
138 | c = 0; |
139 | p = new_p; |
140 | while (1) { |
141 | p = strchr(p, new_p[i]); |
142 | if (p == NULL) { |
143 | break; |
144 | } |
145 | c++; |
146 | p++; |
147 | if (!*p) { |
148 | break; |
149 | } |
150 | } |
151 | /* More than 50% similar characters ? */ |
152 | if (c*2 >= length) { |
153 | return "too many similar characters"; |
154 | } |
155 | } |
156 | |
157 | size = CONFIG_PASSWORD_MINLEN + 2*CATEGORIES; |
158 | for (i = 1; i <= LAST_CAT; i <<= 1) |
159 | if (mixed & i) |
160 | size -= 2; |
161 | if (length < size) |
162 | return "too weak"; |
163 | |
164 | if (old_p && old_p[0]) { |
165 | /* check vs. old password */ |
166 | if (string_checker(new_p, old_p)) { |
167 | return "similar to old password"; |
168 | } |
169 | } |
170 | |
171 | return NULL; |
172 | } |
173 | |
174 | int FAST_FUNC obscure(const char *old, const char *newval, const struct passwd *pw) |
175 | { |
176 | const char *msg; |
177 | |
178 | msg = obscure_msg(old, newval, pw); |
179 | if (msg) { |
180 | printf("Bad password: %s\n", msg); |
181 | return 1; |
182 | } |
183 | return 0; |
184 | } |
185 | |
186 | #if ENABLE_UNIT_TEST |
187 | |
188 | /* Test obscure_msg() instead of obscure() in order not to print anything. */ |
189 | |
190 | static const struct passwd pw = { |
191 | .pw_name = (char *)"johndoe", |
192 | .pw_gecos = (char *)"John Doe", |
193 | }; |
194 | |
195 | BBUNIT_DEFINE_TEST(obscure_weak_pass) |
196 | { |
197 | /* Empty password */ |
198 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "", &pw)); |
199 | /* Pure numbers */ |
200 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "23577315", &pw)); |
201 | /* Similar to pw_name */ |
202 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "johndoe123%", &pw)); |
203 | /* Similar to pw_gecos, reversed */ |
204 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "eoD nhoJ^44@", &pw)); |
205 | /* Similar to the old password */ |
206 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "d4#21?'S", &pw)); |
207 | /* adjacent letters */ |
208 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "qwerty123", &pw)); |
209 | /* Many similar chars */ |
210 | BBUNIT_ASSERT_NOTNULL(obscure_msg("Ad4#21?'S|", "^33Daaaaaa1", &pw)); |
211 | |
212 | BBUNIT_ENDTEST; |
213 | } |
214 | |
215 | BBUNIT_DEFINE_TEST(obscure_strong_pass) |
216 | { |
217 | BBUNIT_ASSERT_NULL(obscure_msg("Rt4##2&:'|", "}(^#rrSX3S*22", &pw)); |
218 | |
219 | BBUNIT_ENDTEST; |
220 | } |
221 | |
222 | #endif /* ENABLE_UNIT_TEST */ |
223 |